1. Field of the Invention
The present invention relates generally to ink compositions used in inkjet imaging printheads and, more particularly, to a system and method for identifying a prescribed inkjet ink.
2. Description of the Related Art
An inkjet imaging system, such as an inkjet printing system, forms an image on a print medium by ejecting ink from a plurality of ink jetting nozzles of an inkjet printhead to form a pattern of ink dots on the print medium. Inkjet printing is accomplished without contact between the printing system and the print medium. Such printing system typically includes a permanent or semi-permanent printhead and one or more ink cartridges in which the ink supplied to the printhead is stored. The ink cartridge may be replaced once consumed during the printing operation.
U.S. Pat. Nos. 5,656,071 & 6,646,024, assigned to the assignee of the present invention, indicate an ongoing recognition that different ink compositions can differently affect print quality and printer maintenance problems. Thus, the composition of inks used in an inkjet printing system has been of long-standing concern. This is especially true where a printer manufacturer wants to offer customers a warranty/service policy for its printing systems. To do this the manufacturer needs to be able to stipulate as a condition that a particular ink composition has to be used and to detect when this condition is not being fulfilled. Hence, there is a need for a way to identify whether the prescribed composition of ink is actually being employed in a printing system that a manufacturer sells and services under its warranty/service policy.
It is known from U.S. Pat. No. 6,293,143 also assigned to the assignee of the present invention, to add fluorescent material to ink to assist in sensing a low ink level in an ink cartridge. The ink level sensing apparatus of the '143 patent is employed in association with an ink cartridge having an ink chamber containing ink and substantially insoluble fluorescent material in the ink. The fluorescent material has a specific gravity which is sufficiently lower than the ink such that the fluorescent material floats at or near the surface of the ink to provide an interface between it and the ink.
The apparatus of the '143 patent includes a light source, such as a light emitting diode (LED), for emitting substantially visible light of a first wavelength bandwidth along a light path through a substantially transparent side panel of the cartridge adjacent the ink chamber. The apparatus of the '143 patent also includes a photo sensor, such as a phototransistor, for detecting light emissions from the fluorescent material in the ink excited by the light of the first wavelength bandwidth when the material crosses the light path, the detected light emissions from the fluorescent material being of a second wavelength bandwidth different from and higher than the first wavelength bandwidth.
The apparatus of the '143 patent further includes a filter between the fluorescent material and the photo sensor for blocking light within the first wavelength bandwidth emitted by the light emitter and passing light within the second wavelength bandwidth such as emitted by the fluorescent material. The primarily visible light emitted by the light emitter and received by the photo sensor has to travel through the transparent wall of the ink cartridge in going to and from the fluorescent material in the ink in the cartridge. A digital output signal generated by the photo sensor is sent to a printer control to signal a low ink level alarm which may be an audible or visible signal, a message on a computer monitor, etc., or a signal to terminate printing operations.
However, this approach is concerned with sensing when an ink cartridge is almost empty by detecting the presence of an interface between the ink and a non-soluble fluorescent material. This approach is not concerned with sensing a given level of emissions from a fluorescent material in order to identify the ink about to be used nor is it concerned with whether the ink should or should not he used in the first instance. Thus, the need remains for an approach to identifying whether the prescribed composition of ink is about to be used in the printing system that a manufacturer sells and services tender its warranty/service policy.